Asymmetric membranes having a large pore size on the upstream surface, a smaller pore size on the downstream surface, and an average pore size that decreases from the upstream surface in a direction toward the downstream surface (such membranes can be referred to as having a “V-shaped pore structure”) are known in the art. However, conventional asymmetric membranes may exhibit reduced performance, capacity, and lifespan.
Accordingly, there is a need for improved asymmetric membranes.